US20200277750A1 - Method and system for controlling wheel loader - Google Patents
Method and system for controlling wheel loader Download PDFInfo
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- US20200277750A1 US20200277750A1 US16/802,988 US202016802988A US2020277750A1 US 20200277750 A1 US20200277750 A1 US 20200277750A1 US 202016802988 A US202016802988 A US 202016802988A US 2020277750 A1 US2020277750 A1 US 2020277750A1
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Images
Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F1/00—General working methods with dredgers or soil-shifting machines
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
- E02F3/431—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like
- E02F3/434—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like providing automatic sequences of movements, e.g. automatic dumping or loading, automatic return-to-dig
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W60/00—Drive control systems specially adapted for autonomous road vehicles
- B60W60/001—Planning or execution of driving tasks
- B60W60/0025—Planning or execution of driving tasks specially adapted for specific operations
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F7/00—Equipment for conveying or separating excavated material
- E02F7/04—Loading devices mounted on a dredger or an excavator hopper dredgers, also equipment for unloading the hopper
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/2025—Particular purposes of control systems not otherwise provided for
- E02F9/2029—Controlling the position of implements in function of its load, e.g. modifying the attitude of implements in accordance to vehicle speed
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/2025—Particular purposes of control systems not otherwise provided for
- E02F9/205—Remotely operated machines, e.g. unmanned vehicles
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
- E02F9/2062—Control of propulsion units
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
- E02F9/2079—Control of mechanical transmission
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
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- E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
- E02F9/2083—Control of vehicle braking systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2520/00—Input parameters relating to overall vehicle dynamics
- B60W2520/26—Wheel slip
Definitions
- Example embodiments relate to a method and a system for controlling a wheel loader. More particularly, example embodiments relate to a method of performing an autonomous excavation work for a wheel loader and a system for controlling a wheel loader.
- Wheel loaders are widely used at construction sites to excavate aggregate such as dirt, sand, gravel and the like and load it into dump truck. Since the aggregate may be inhomogeneous loose soil or a somewhat compact material, the excavation work for digging the aggregate may be easy or difficult depending on the type of the aggregate. Further, load applied to the wheel loader may vary depending on the aggregate, which may result in tire slip. In particular, when the autonomous wheel loader performs the autonomous excavation work, the tire slip may occur thereby reducing the tire life and deteriorating productivity.
- Example embodiments provide a method of controlling a wheel loader capable of performing an autonomous excavation function to improve fuel efficiency and productivity.
- Example embodiments provide a control system of a wheel loader for performing the method.
- the wheel loader in a method of controlling a wheel loader, is moved forwards such that a bucket penetrates into an aggregate to perform an excavation work.
- Signals able to be used to determine tire slip of the wheel loader are obtained during the excavation work.
- Prediction algorithms obtained through training are performed to determine whether or not the tire slip occurs.
- an engine speed is decreased and the bucket is lifted to remove the tire slip.
- the bucket is moved along a predetermined autonomous excavation trajectory when the tire slip is removed.
- performing the prediction algorithms may include performing algorithms trained using data on a tire tractive force and a bucket breakout force as learning data for the tire slip determination.
- obtaining the signals able to be used to determine the tire slip of the wheel loader may include obtaining a first group of signals required for calculating a tractive force of the tire, and obtaining a second group of signals required for calculating a breakout force of the bucket.
- the first group of signals may include an engine rotational speed signal, a turbine rotational speed signal of a torque converter, a speed step signal of a transmission, a vehicle speed signal and a wheel rotational speed signal
- the second group of signals may include a stroke signal of a boom cylinder, a stroke signal of a bucket cylinder and a pressure signal of the boom cylinder.
- the wheel rotational speed signal may be obtained from an encoder installed in the tire.
- moving the wheel loader forwards to perform the excavation work may include increasing an engine speed without an operator stepping on an acceleration pedal.
- lifting the bucket when the tire slip occurs may include increasing a stroke of a boom cylinder.
- the method may further include determining a time when the bucket penetrates into the aggregate and a speed step of a transmission is shifted down from second step to first step as an entry time of the excavation work.
- the method may further include terminating the autonomous excavation work mode when an angle of the bucket is at the maximum crowd state.
- a control system for a wheel loader includes a plurality of sensors installed respective in an engine and a work apparatus and a travel apparatus driven by the engine to detect signals able to be used to determine tire slip of the wheel loader, a control apparatus configured to output a control signal for performing an autonomous excavation work mode of the wheel loader, perform prediction algorithms obtained through training on the signals received from the sensors to determine whether or not the tire slip occurs and output first and second tire slip removal control signals so as to remove the tire slip within a desired value, an engine control device configured to decrease an engine rotational speed according to the first tire slip removal control signal, and a work control device configured to lift a bucket of the wheel loader according to the second tire slip removal control signal.
- control apparatus may include a data receiver configured to receive the signals from the sensors, a determiner configured to perform neural network algorithms on the signals to determine whether or not the tire slip occurs, and an output portion configured to output the first and second tire slip removal control signals to the engine control device and the work control device respectively.
- the sensors may include a first group of sensors for detecting signals required for calculating a tractive force of a tire and a second group of sensors for detecting signals required for calculating a breakout force of the bucket.
- the first group of sensors may include at least one of an engine speed sensor, a turbine rotational speed sensor of a torque converter, a sensor for detecting speed step of a transmission, a vehicle speed sensor and a wheel speed detection sensor, and a second group of sensors may include at least one of a boom angle sensor, a bucket angle sensor and a boom cylinder pressure sensor.
- the wheel speed detection sensor may include an encoder installed in the tire.
- control apparatus may output an acceleration pedal output signal having a predetermined increase ratio value to the engine control device when the autonomous excavation work mode is entered, to increase the engine rotational speed.
- the first tire slip removal control signal may include an acceleration pedal output signal having a predetermined decrease ratio value.
- the second tire slip removal control signal may include a pilot pressure signal for increasing a stroke of a boom cylinder.
- control apparatus may determine a time when the bucket penetrates into an aggregate and speed step of a transmission is shifted down from second step to first step as an entry time of the autonomous excavation work mode.
- control apparatus may determine a time when an angle of the bucket is at the maximum crowd state as an end point of the autonomous excavation work mode.
- a wheel loader may be controlled to perform an autonomous excavation work without an operator pressing an acceleration pedal when entering an autonomous excavation work mode.
- tire slip of the wheel loader may be determined by using prediction algorithm obtained through training such as neural network algorithms on signals received from sensors installed on the wheel loader, and when it is determined that the tire slip occurs, an engine speed may be decreased and the bucket may be lifted to remove the tire slip within a desired range.
- Artificial neural network algorithms for a digging force and a tractive force that change according to the type and state of the aggregate may be used to control real-time equipment to thereby implement full autonomous excavation function.
- tire product life may be prevented from shortening due to excessive slippage of tires and optimized excavation trajectory control may be performed regardless of the operator's skill to thereby improve productivity.
- FIG. 1 is a side view illustrating a wheel loader in accordance with example embodiments.
- FIG. 2 is a block diagram illustrating a system for controlling the wheel loader in FIG. 1 .
- FIG. 3 is a block diagram illustrating a control system for a wheel loader in accordance with example embodiments.
- FIG. 4 is a block diagram illustrating a control apparatus in FIG. 3 .
- FIG. 5 is a view illustrating a neural network circuit in a tire slip determiner in FIG. 4 .
- FIG. 6 is a view illustrating a signal transfer in each layer of the neural network in FIG. 5 .
- FIG. 7 is a graph illustrating a tractive force of a tire according to an acceleration pedal output signal inputted to an engine control unit from the control apparatus in FIG. 3 .
- FIG. 8 is a graph illustrating a height of a buck according to a pilot pressure signal inputted to a work control apparatus from the control apparatus in FIG. 3 .
- FIG. 9 is a flow chart illustrating a method of controlling a wheel loader in accordance with example embodiments.
- FIG. 10 is views illustrating an entry time of an auto-excavation work mode in accordance with example embodiments.
- FIG. 11 is graphs illustrating a tractive force of tire and a breakout force of a bucket in accordance with example embodiments.
- Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments are shown.
- Example embodiments may, however, be embodied in many different forms and should not be construed as limited to example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example embodiments to those skilled in the art.
- the sizes and relative sizes of components or elements may be exaggerated for clarity.
- first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of example embodiments.
- spatially relative terms such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
- FIG. 1 is a side view illustrating a wheel loader in accordance with example embodiments.
- FIG. 2 is a block diagram illustrating a system for controlling the wheel loader in FIG. 1 .
- a wheel loader 10 may include a front body 12 and a rear body 14 connected to each other.
- the front body 12 may include a work apparatus and a front wheel 160 .
- the rear body 14 may include a driver cabin 40 , an engine bay 50 and a rear wheel 162 .
- the work apparatus may include a boom 20 and a bucket 30 .
- the boom 20 may be freely pivotally attached to the front body 12
- the bucket 30 may be freely pivotally attached to an end portion of the boom 20 .
- the boom 20 may be coupled to the front body 12 by a pair of boom cylinders 22 , and the boom 20 may be pivoted upwardly and downwardly by expansion and contraction of the boom cylinders 22 .
- a tilt arm 34 may be freely rotatably supported on the boom 20 , almost at its central portion.
- One end portion of the tilt arm 34 may be coupled to the front body 12 by a pair of bucket cylinders 32 and another end portion of the tilt arm 34 may be coupled to the bucket 30 by a tilt rod, so that the bucket 30 may pivot (crowd and dump) as the bucket cylinder 32 expands and contracts.
- the front body 12 and the rear body 14 may be rotatably connected to each other through a center pin 16 so that the front body 12 may swing side to side with respect to the rear body 14 by expansion and contraction of a steering cylinder (not illustrated).
- a travel apparatus for propelling the wheel loader 10 may be mounted at the rear body 14 .
- An engine 100 may be provided in the engine bay 50 to supply an output power to the travel apparatus.
- the travel apparatus may include a torque converter 120 , a transmission 130 , a propeller shaft 150 , axles 152 , 154 , etc.
- the output power of the engine 100 may be transmitted to the front wheel 160 and the rear wheel 162 through the torque converter 120 , the transmission 130 , the propeller shaft 150 and the axles 152 and 154 , and thus the wheel loader 10 may travels.
- the output power of the engine 100 may be transmitted to the transmission 130 through the torque converter 120 .
- An input shaft of the torque converter 120 may be connected to an output shaft of the engine 100 , and an output shaft of the torque converter 120 may be connected to the transmission 130 .
- the torque converter 120 may be a fluid clutch device including an impeller, a turbine and a stator.
- the transmission 130 may include hydraulic clutches that shift speed steps between first to fourth speeds, and rotation of the output shaft of the torque converter 120 may be shifted by the transmission 130 . The shifted rotation may be transmitted to the front wheel 160 and the rear wheel 162 through the propeller shaft 150 and the axles 152 and 154 and thus the wheel loader may travel.
- the torque converter 120 may have a function to increase an output torque with respect to an input torque, i.e., a function to make the torque ratio 1 or greater.
- Nt/Ni a ratio of the number of rotations Nt of the output shaft of the torque converter 120 to the number of rotations Ni of the input shaft of the torque converter 120 .
- the torque ratio may be increased and thus the vehicle may be allowed to travel with a greater travel driving force (traction force).
- the transmission 130 may include a forward hydraulic clutch for forward movement, a reverse hydraulic clutch for reverse movement, and first to fourth hydraulic clutches for the first to the fourth speeds.
- the hydraulic clutches may be each engaged or released by pressure oil (clutch pressure) supplied via a transmission control unit (TCU) 140 .
- the hydraulic clutches may be engaged when the clutch pressure supplied to the hydraulic clutches is increased, while the hydraulic clutches may be released when the clutch pressure is decreased.
- a speed step may be shifted up by one step.
- the speed step may be shifted down by one step.
- a variable capacity hydraulic pump 200 for supplying a pressurized hydraulic fluid to the boom cylinder 22 and the bucket cylinder 32 may be mounted at the rear body 14 .
- the variable capacity hydraulic pump 200 may be driven using at least a portion of the power outputted from the engine 100 .
- the output power of the engine 100 may drive the hydraulic pump 200 for the work apparatus and a hydraulic pump (not illustrated) for the steering cylinder via a power take-off (PTO) such as a gear train 110 .
- PTO power take-off
- a pump control device may be connected to the variable capacity hydraulic pump 200 , and the hydraulic fluid discharged from the variable capacity hydraulic pump 200 may be controlled by the pump control device.
- a main control valve (MCV) including a boom control valve 210 and a bucket control valve 212 may be installed on a hydraulic circuit of the hydraulic pump 200 .
- the hydraulic fluid discharged from the hydraulic pump 200 may be supplied to the boom cylinder 22 and the bucket cylinder 32 through the boom control valve 210 and the bucket control valve installed in a hydraulic line 202 respectively.
- the main control valve (MCV) may supply the hydraulic fluid discharged from the hydraulic pump 200 to the boom cylinder 22 and the bucket cylinder 32 according to a pilot pressure in proportion to an operation rate of an operating lever.
- the boom 20 and the bucket 30 may be driven by the pressure of the hydraulic fluid discharged from the hydraulic pump 200 .
- a maneuvering device may be provided within the driver cabin 40 .
- the maneuvering device may include an acceleration pedal 142 , a brake pedal, an FNR travel lever, the operating levers for operating the cylinders such as the boom cylinder 22 and the bucket cylinder 32 , etc.
- the wheel loader 10 may include a traveling operating system for driving the travel apparatus via the PTO and a hydraulic operating system for driving the work apparatus such as the boom 20 and the bucket 30 using the output power of the engine 100 .
- a control apparatus 300 for the wheel loader 10 such as a portion of a vehicle control unit (VCU) or a separate control unit may be mounted in the rear body 14 .
- the control apparatus 300 may include an arithmetic processing unit having a CPU which executes a program, a storage device such as a memory, other peripheral circuit, and the like.
- the control apparatus 300 may receive signals from various sensors (detectors) which are installed in the wheel loader 10 .
- the control apparatus 300 may be connected to an engine speed sensor 104 for detecting a rotational speed of the engine, an acceleration pedal detection sensor 143 for detecting an operation amount of the acceleration pedal 142 , a brake pedal detection sensor for detecting an operation amount of the brake pedal, and an FNR travel lever position sensor for detecting a manipulation position of the FNR travel lever, for example, forward (F), neutral (N) and reverse (R).
- the control apparatus 300 may receive an engine rotational speed signal and an acceleration pedal signal from an engine control unit (ECU) connected to the engine speed sensor 104 and the acceleration pedal detection sensor 143 . Further, the control apparatus 300 may receive a speed step signal of the transmission through the transmission control unit (TCU) 140 .
- ECU engine control unit
- TCU transmission control unit
- control apparatus 300 may be connected to a turbine rotational speed sensor 122 for detecting a rotational speed of the turbine of the torque converter 120 , a vehicle speed sensor 132 for detecting a rotational speed of an output shaft of the transmission 130 , i.e., and a wheel speed detection sensors 170 , 172 for detecting a wheel speed.
- the wheel speed detection sensors 170 , 172 may include an encoder installed in a tire.
- the control apparatus 300 may be connected to a GPS receiver installed in the wheel loader, to receive a current speed of the vehicle.
- control apparatus 300 may be connected to a pressure sensor 204 installed in the hydraulic line 202 in front end of the main control valve (MCV) to detect a pressure of the hydraulic fluid discharged from the hydraulic pump 200 , and a boom cylinder pressure sensor 222 for detecting a cylinder head pressure at a head of the boom cylinder 22 . Furthermore, the control apparatus 300 may be connected to a boom angle sensor 224 for detecting a rotational angle of the boom 20 and a bucket angle sensor 234 for detecting a rotational angle of the bucket 30 .
- MCV main control valve
- the signals detected by the sensors may be inputted into the control apparatus 300 .
- the control apparatus 300 may select one or more signals of the signals received from the sensors installed in the wheel loader 10 , perform prediction algorithms obtained through training such as neural network algorithms to determine whether or not tire slip occurs. Further, the control apparatus 300 may output a control signal to the engine control unit (ECU), the transmission control unit (TCU) 140 , and the pump control device (EPOS), etc, to selectively control the travel apparatus and the work apparatus of the wheel loader 10 based on the occurrence of the tire slip.
- ECU engine control unit
- TCU transmission control unit
- EPOS pump control device
- FIG. 3 is a block diagram illustrating a control system for a wheel loader in accordance with example embodiments.
- FIG. 4 is a block diagram illustrating a control apparatus in FIG. 3 .
- FIG. 5 is a view illustrating a neural network circuit in a tire slip determiner in FIG. 4 .
- FIG. 6 is a view illustrating a signal transfer in each layer of the neural network in FIG. 5 .
- FIG. 7 is a graph illustrating a tractive force of a tire according to an acceleration pedal output signal inputted to an engine control unit from the control apparatus in FIG. 3 .
- FIG. 8 is a graph illustrating a height of a buck according to a pilot pressure signal inputted to a work control apparatus from the control apparatus in FIG. 3 .
- a control system for a wheel loader may include a plurality of sensors, a control apparatus 300 for performing an autonomous excavation work mode, a travel apparatus control device and a work apparatus control device.
- the sensors may be installed in the engine 100 , the work apparatus and the travel apparatus to detect signals representing state information of the wheel loader.
- the control system form a wheel loader may include a first group of sensors for detecting signals required for calculating a tractive force of a tire of the wheel loader 10 and a second group of sensors for detecting signals required for calculating a breakout (digging) force of a bucket.
- the first group of sensors may include the engine speed sensor 104 , the turbine rotational speed sensor 122 , the sensor for detecting the speed step of the transmission, the vehicle speed sensor 132 , the wheel speed detection sensor, etc.
- the second group of sensors may include the boom angle sensor 224 , the bucket angle sensor 234 , the boom cylinder pressure sensor 222 , etc.
- the control apparatus 300 may include a data receiver 310 , a determiner 320 and an output portion 330 .
- the data receiver 310 may receive signals from the sensors. Additionally, the data receiver 310 may receive an autonomous excavation work mode selection signal from a selection portion 302 . When the autonomous excavation work mode is selected by an operator, the selection portion 302 may output the autonomous excavation work mode selection signal to the control apparatus 300 . Further, the operator may select detail working conditions of the autonomous excavation work mode through the selection portion 302 .
- the detail working conditions may include an excavation workload, an excavation work speed, an allowable range of tire slip, and the like.
- the determiner 320 may determine the entry time and end point of the autonomous excavation work mode.
- the determiner 320 may determine a time when the bucket 30 penetrates into the aggregate as the entry time of the autonomous excavation work mode.
- the bucket 30 digs the aggregate and load is applied to the travel apparatus by the reaction force, and the speed step of the transmission 130 is shifted down to the first step, it may be determined as the entry time of the autonomous excavation work mode.
- the angle of the bucket 30 is at the maximum crowd state, it may be determined as the end point of the autonomous excavation work mode.
- determiner 320 may include neural network circuits that perform neural network algorithms to determine whether or not the tire slip occurs.
- the neural network circuit may include multilayer perceptrons having a multi-input layer, a hidden layer and an output layer. Neurons may be arranged in each layer, and the neurons in each layer may be connected by connection weights. Input data may be inputted to the neurons in the input layer and transferred to the output layer though the hidden layer.
- Training the neural network algorithm may be a process of tuning the interconnection weights between each nodes in order to minimize an error between an expectation value and an output value of the neural network algorithms for a specific input (actual detected data).
- back propagation algorithm may be used for training the neural networks.
- the neural network circuits of the determiner 320 may vary the connection weights between the input layer, the hidden layer and the output layer using pre-collected data to provide neural network algorithms as prediction models.
- data obtained from the first group of sensors and the second group of sensors may be accumulated and may be used as learning data.
- the tire slip moments may be recorded on the basis of the number of the tire revolutions obtained from the external encoder 170 , 172 installed in the tire, and tire slip occurrence data may be accumulated and used as learning data.
- the GPS speed of the wheel loader 10 , the breakout force of the bucket 30 , the acceleration pedal value from the engine control unit 400 , etc. may be used as supervised leaning data for the tire slip determination.
- the tire tractive force is greater than a predetermined value and the acceleration pedal signal value does not decrease (not have a negative rate of change)
- data when the tire tractive force decreases by a predetermined level or more may be used as supervised learning data for the tire slip determination.
- data when the bucket breakout force increases and the number of the tire revolutions increases may be used as supervised learning data for the tire slip determination.
- the sensor signal weight of the artificial neural network logic may be determined and the tire slip may be determined from the sensor signals.
- the output portion 330 may output an autonomous excavation work mode control signal for the autonomous excavation work mode and first and second tire slip removal control signals for removing the tire slip within a desired value.
- the autonomous excavation work mode control signal may include an acceleration pedal output signal having a predetermined increase ratio value.
- the output portion 330 may output the autonomous excavation work mode control signal to the engine control device 400 when the autonomous excavation work mode is entered.
- the engine control device 400 may increase the engine speed by controlling a fuel injector 102 according to the autonomous excavation work mode control signal without the operator pressing the acceleration pedal.
- the first tire slip removal control signal may include an acceleration pedal output signal having a predetermined decrease ratio value.
- the output portion 330 may output the acceleration pedal output signal to the engine control device 400 when the tire slip occurs.
- the engine control device 400 may decrease the engine speed by controlling the fuel injector 102 according to the first tire slip removal control signal.
- the second tire slip removal control signal may include a pilot pressure signal for increasing a stroke of the boom cylinder 22 .
- the output portion 330 may output the pilot pressure signal to the work control apparatus, that is, the boom control valve 210 of the main control valve MCV when the tire slip occurs.
- the boom control valve 210 may increase the stroke of the boom cylinder 210 according to the pilot pressure signal to increase a height of the bucket 30 .
- the control apparatus 300 may further include a storage portion.
- the storage portion may store data required for learning in a predictive model and calculation in the neural network algorithm which are performed in the determiner 330 , a control map required for determination of the control signal which is performed in the output portion 330 , etc.
- the fuel injection amount may be decreased and thus the engine speed may be also decreased.
- the tractive force of the tire may be decreased according to the acceleration pedal decrease ratio (%) (point A->point B). As the tractive force of the tire is decreased the tire slip may be removed.
- the stroke of the boom cylinder 22 may be increased, thereby raising the height of the bucket 30 .
- the height of the bucket 30 may be increased according to the stroke increase rate of the boom cylinder 22 (point C->point D).
- the bucket 30 may lift the aggregate upwards and thus the load on the tire may be increased to thereby remove the tire slip.
- control apparatus 300 of the wheel loader may control the wheel loader 10 to perform the autonomous excavation work without the operator pressing the acceleration pedal when entering the autonomous excavation work mode.
- control apparatus 300 of the wheel loader may determine the tire slip of the wheel loader 10 by using prediction algorithm obtained through training such as neural network algorithms on the signals received from the sensors installed on the wheel loader 10 , and when it is determined that the tire slip occurs, may decrease the engine speed and lift the bucket 30 to remove the tire slip.
- the control apparatus 300 of the wheel loader may learn data of the tire slip by using the artificial neural network algorithms for the digging force and tractive force that change according to the type and state of the aggregate to adjust the determination weight of the equipment sensor signal and to control the real-time equipment to thereby implement full autonomous excavation function.
- tire product life may be prevented from shortening due to excessive slippage of tires and optimized excavation trajectory control may be performed regardless of the operator's skill to thereby improve productivity.
- FIG. 9 is a flow chart illustrating a method of controlling a wheel loader in accordance with example embodiments.
- FIG. 10 is views illustrating an entry time of an auto-excavation work mode in accordance with example embodiments.
- FIG. 11 is graphs illustrating a tractive force of tire and a breakout force of a bucket in accordance with example embodiments.
- an entry time of an autonomous excavation work mode may be determined (S 100 ), and when the autonomous excavation work mode is entered, a wheel loader 10 may be accelerated to perform an excavation work (S 110 ).
- a time when a bucket 30 penetrates into an aggregate may be determined as the entry time of the autonomous excavation work mode.
- the wheel loader 10 may move forwards and start to penetrate into the aggregate M.
- An angle of a bottom face of the bucket 30 may be kept parallel with the ground, and the boom 20 may be lowered so that the bottom face of the bucket 30 approaches closely to the ground.
- the bucket 30 may dig the aggregate, and then, load is applied to a travel apparatus by the reaction force and the speed step of a transmission 130 is shifted down to the first step, it may be determined as the entry time of the autonomous excavation work mode.
- the wheel loader 10 may be accelerated to perform an autonomous excavation work.
- a control apparatus 300 may output an autonomous excavation work mode control signal to an engine control device 400 when the autonomous excavation work mode is entered.
- the autonomous excavation work mode control signal may include an acceleration pedal output signal having a predetermined increase ratio value.
- the engine control device 400 may increase an engine speed by controlling a fuel injector 102 according to the autonomous excavation work mode control signal without the operator pressing the acceleration pedal.
- prediction algorithms obtained through training may be performed to determine whether or not tire slip occurs.
- the signals able to be used to determine the tire slip of the wheel loader 10 may be obtained.
- the first group of signals may include an engine rotational speed signal, a turbine rotational speed signal of a torque converter, a speed step signal of a transmission, a vehicle speed signal and a wheel rotational speed signal.
- the second group of signals may include a stroke signal of a boom cylinder, a stroke signal of a bucket cylinder and a pressure signal of the boom cylinder.
- Data obtained from the first group of signals and the second group of signals may be accumulated to be used as learning data.
- the tire slip moments obtained from an external encoder 170 , 172 installed in the tire may be recorded, and tire slip occurrence data may be accumulated to be used as learning data.
- the GPS speed of the wheel loader 10 , the tractive force of the tire, the breakout force of the bucket 30 , the acceleration pedal value from the engine control unit 400 , etc. may be used as supervised leaning data for the tire slip determination.
- the sensor signal weight of the artificial neural network logic may be determined and the tire slip may be determined from the sensor signals.
- the engine speed of the wheel loader 10 may be decreased and the bucket 30 may be lifted until the tire slip is removed within a desired value ( 130 ).
- control apparatus 300 may output a first tire slip removal control signal to the engine control device 400 when the tire slip occurs.
- the engine control device 400 may decrease the engine speed by controlling the fuel injector 102 according to the first tire slip removal control signal.
- a fuel injection amount may be decreased in response to an acceleration pedal output signal having a predetermined decrease ratio value, and thus, the engine speed may be also decreased.
- the engine control device 400 may increase the engine speed by controlling a fuel injector 102 according to the autonomous excavation work mode control signal without the operator pressing the acceleration pedal. In this case, the tractive force of the tire may be decreased according the acceleration pedal decrease ratio and thus the tire slip may be removed.
- control apparatus 300 may output a second tire slip removal control signal to a work control apparatus, that is, a boom control valve 210 of a main control valve MCV when the tire slip occurs.
- the second tire slip removal control signal may include a pilot pressure signal for increasing a stroke of the boom cylinder 22 .
- the boom control valve 210 may increase the stroke of the boom cylinder 210 according to the pilot pressure signal to increase a height of the bucket 30 .
- the stroke of the boom cylinder 22 may be increased in response to the pilot pressure signal, thereby increasing the height of the bucket 30 .
- the height of the bucket 30 may be increased according to the stroke increase rate of the boom cylinder 22 .
- the bucket 30 may lift the aggregate upwards and thus the load on the tire may be increased to thereby remove the tire slip.
- graph G 1 represents the tire tractive force and graph G 2 represents the bucket digging force, and graphs G 3 and G 4 represent speeds of left and right wheels.
- the tire tractive force decreases and the GPS speed of the wheel loader 10 is constant or decreases, while the tire rotational speed (wheel speed) increases while vibrating rapidly.
- the tire slippage may disappear as the friction force with the ground increases, and thus, the tractive force may be increased again and the digging operation may be done smoothly.
- the bucket 30 may be moved along a predetermined autonomous digging trajectory, and the autonomous excavation work mode may be terminated.
- control apparatus 300 may output the autonomous excavation control signal to the engine control device 400 and the work control device when the tire slip disappears.
- the strokes of the boom cylinder 22 and the bucket cylinder 32 may be controlled such that the end portion of the bucket 30 moves along the predetermined digging trajectory.
- the autonomous excavation work mode may be terminated.
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- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Mechanical Engineering (AREA)
- Automation & Control Theory (AREA)
- Human Computer Interaction (AREA)
- Transportation (AREA)
- Operation Control Of Excavators (AREA)
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CN113818505A (zh) * | 2021-11-24 | 2021-12-21 | 徐工集团工程机械股份有限公司科技分公司 | 一种装载机铲掘防滑控制方法、系统及装置 |
WO2023133959A1 (zh) * | 2022-01-17 | 2023-07-20 | 华侨大学 | 一种分布式的全电驱动系统及其装载机 |
WO2023182320A1 (ja) * | 2022-03-24 | 2023-09-28 | 日立建機株式会社 | ホイールローダの制御装置 |
CN116976104A (zh) * | 2023-07-27 | 2023-10-31 | 徐工集团工程机械股份有限公司科技分公司 | 装载机行驶控制方法、装置及系统 |
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CN113291142B (zh) * | 2021-05-13 | 2022-11-11 | 广西大学 | 一种智能行驶系统及其控制方法 |
JP2023006408A (ja) * | 2021-06-30 | 2023-01-18 | 株式会社小松製作所 | 作業機械、及び、作業機械を制御するための方法。 |
CN115450278B (zh) * | 2022-09-16 | 2023-09-22 | 江苏电子信息职业学院 | 一种装载机铲斗辅助铲掘控制方法 |
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EP3702538A1 (de) | 2020-09-02 |
CN111622293A (zh) | 2020-09-04 |
CN111622293B (zh) | 2022-10-04 |
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